9.2- IMPACT FORCES

Question 1

If an object is stationary + impact causes it to accelerate what is the equation for force of the impact F?

Answer 1

F = change of momentum / contact time = mv / t

Question 2

If an object is moving + impact changes its velocity what is the equation for the force of impact F?

Answer 2

F = change of momentum / contact time = mv -mu / t

Question 3

What can the variation of impact force with time on ball be recorded using? (force-time graphs for impacts)

Answer 3

force sensor connected using suitably long wires or radio link to computer

Question 4

What is the force sensor attached to? (force-time graphs for impacts)

Answer 4

object that causes impact

Question 5

When a ball hits a wall + rebounds, why does its momentum change direction?

Answer 5

due to impact

Question 6

If the ball hits the wall normally, how does it rebound?

Answer 6

rebounds normally so direction of its momentum reversed

Question 7

What is the velocity + momentum like after the impact as it rebounds?

Answer 7

velocity + momentum after impact in opposite direction to velocity before impact + so has opposite sign

Question 8

What is the equation for the impact force F for rebound impacts?

Answer 8

F = change of momentum / contact time = (-mv) - (mu) / t

Question 9

What is the equation for the impact force F for rebound impacts when there is no loss of speed on impact?

Answer 9

F = (-mv) - (mu) / t = -2mu / t

Question 10

Is there is a loss in speed for an impact in which initial + final direction of ball are at same angle θ to nromal?

Answer 10

no

Question 11

What is the normal component of the initial velocity?

Answer 11

+u cosθ

Question 12

What is the normal component of the final velocity?

Answer 12

-u cosθ

Question 13

What is the change of momentum of ball with same angle?

Answer 13

-2 mu cosθ